1. Field of the Invention
The present invention is directed to managing and monitoring traffic and capacity in a packet-switched digital network. More particularly, the present invention is directed to capturing traffic log data, and graphically displaying network operation characteristics based on the traffic log data.
2. Background of the Invention
Mobitex is a digital wireless data network technology that was developed in 1984 and has since seen explosive growth. The Mobitex wireless network technology is recognized as an international data communication standard. It is a secure, reliable, two-way digital wireless packet switching network ideal for a variety of data communication applications, such as email and information broadcasting.
Presently there are 28 Mobitex networks operating in 22 countries throughout the world. FIG. 1 shows a typical Mobitex network 100 which has a pyramidal topology with a single Network Control Center (NCC) 10, a national exchange 15, several regional exchanges 20 (referred to herein as “MHXs”), several local exchanges 30 (referred to herein as “MOXs”) and hundreds (or even thousands) of base stations 40 linked, or interconnected, to each other using high speed conventional or fiber optic or microwave communications links. (“MHX” and “MOX”are Swedish acronyms and are well known to those skilled in the art.) Wireless devices 50 communicate with a base station 40 with which it has the best available signal strength. Also, hosts 60a, 60b (e.g., a customer's computer, gateway, etc.) can be connected to Mobitex network 100 via, for example, the well-known X.25 communication protocol, using either dedicated leased circuits or public data networks.
To connect to Mobitex network 100, each radio modem in wireless device 50, or host 60 must have an active Mobitex Access Number (MAN). A MAN is assigned to every user (or device) subscribing (connected) to the Mobitex network. A MAN is analogous to a phone number on a telephone network. Thus, the MAN for a mobile user is stored in the mobile device's radio modem, just as a telephone number is stored inside a cellular phone.
Mobitex network 100 uses a packet-switching technique to transmit data. Each packet in the Mobitex network is called an MPAK (short for “Mobitex packet”) and can have no more than 512 bytes of data. Messages longer than 512 bytes are divided into multiple packets. MPAKs include information about the origin, destination, size, type, and sequence of data to be sent, enabling packets to be transmitted individually, in any order, as traffic permits. Individual packets may travel along different routes, in any order, without interfering with other packets sent over the same frequency by different users. At the receiving end, all packets are accounted for, and reassembled into the original message. Further information about the technical aspects of a conventional Mobitex network can be found in Mobitex Interface Specification (MIS), Ericsson Mobile Data Design AB, Gothenburg, Sweden.
In order to provide network customers with reliable communications service, a network operator is often interested in learning whether capacity remains in the network and/or whether an overload condition has been reached. For this purpose, a conventional Mobitex network implements an alarm scheme to alert personnel at NCC 10 that a problem has been detected in the network. More specifically, each level of network 100 and the interconnecting links all have predetermined capacities. Existing Mobitex tools permit NCC personnel to set alarm condition thresholds with respect to, for example, MPAKs per hour or MPAKs per ten minute period, that travel through a particular network device. If a threshold is exceeded, the NCC receives an alarm that indicates, for example, that a particular base station 40 or MOX 30 exceeded the threshold. NCC 10 may subsequently receive an alarm indicating that the traffic level has fallen below the alarm threshold.
Each of these alarm events is, generally, displayed on a computer screen at NCC 10, one line per alarm. In a typical network of, for example, 2,000 base stations, 80 MOXs and six MHXs, alarms tend to scroll across the display screen without affording NCC personnel any true insight into the state of the network. Indeed, the amount of alarm information can be overwhelming.
To improve on the foregoing network alarm scheme, filters have been implemented to pick out alarms that represent specific information of interest, and display only those alarm events on a separate display screen, or store them in a separate file for later analysis. However, even with the implementation of filters, a network engineer may still have difficulty obtaining real-time or substantive analysis information for purposes of trouble-shooting or monitoring network operations. Indeed, alarm thresholds are often set artificially low and used primarily to indicate when capacity needs to be added. These alarms, therefore, tend to be even less meaningful. Thus, using existing alarm tools, it is apparent from the foregoing that a network engineer cannot “watch” what is happening in network 100. He can only know when a threshold has been hit.
One way to obtain a better view into network 100 is to periodically poll each of the devices in the network. Unfortunately, when this is done, additional traffic is created, thereby decreasing the amount of capacity that is available for customer use. Often such polling from the NCC has priority over customer traffic, thereby effectively ensuring that paying customers are undesirably blocked out of the network.
Further, from time to time, network engineers and operators contemplate network topology changes in view of customer complaints or growth opportunities. It would be highly desirable to have a network operations tool that can assist in analyzing “what-if” scenarios with respect to new nodes or links between nodes.
Accordingly, there is a need for network analysis tools that can provide real-time or near real-time graphical display of the operations of a network, and particularly a Mobitex network, without adding more traffic to the network itself. There is also a need for network operations tools that can help evaluate, in a meaningful way, proposed network topology changes.